Transfer apparatus for exchanging articles between two conveyors

ABSTRACT

Apparatus for transferring molds for ceramic blanks or the like between a first conveyor associated with a molding machine, and a second conveyor which is associated with a drier and receives molds filled with blanks from the first conveyor and delivers empty molds back to it, twice as many molds being disposed one beside the other on the second conveyor as on the first conveyor.

United States Patent Inventors Appl. No. Filed Patented Atsignee Priority Norbert Klimasehka Sclb. Bayer-n;

Josef Poilmnnn. Reichenbach. Bayer-n, both v of. Germany Sept. 8, 1969 Aug. 10, 197 i Gebruder Nelzsch Maschineniabrik Blyern, Germany Sept. 12 1968 Great Britain TRANSFER APPARATUS FOR EXCHANGING ARTICLES BETWEEN TWO CONVEYORS 24 Claims, 13 Drawing Figs.

U.S. Cl. l. 198/20, 198/30. 198/106 Int. Cl. ,.B65g 47/26, 865g 47/52 [50] Field oisenrchn 198/31 AA; 31 AC, 20-. 301 1116 [56] References Cited UNITED STATES PATENTS 1,117,433 11/1914 198/311Ai21 1,356,167 10/1920 N1Vr...-....-. 198/311A21 Primary Examiner-Edward A; Sroka Attorney Karl W1 Fiocks ABSTRACT: A aratus for transferring molds for ceramic blanks or the like between a first eonveyor aseociated with a molding machine, and a second conveyor which is aseoeiated with a drier and receives molds filled With blanks from the (net conveyor and delivers em ty moide back to it, twice as many molds being disposed one beside the other on the econd eonveyor as on the first convey'Or.

PATENTED AUG 1 0 IBYI SHEET 2 BF 6 PATENTED AUG 1 01am SHEEI 3 BF 6 PATENTED AUG] 0:911

SHEET 5 OF 6 Fig. 6e

PATENTED Aus'v 01971 SHEET 5 BF 6 TRANSFER APPARATUS FOR EXCHANGING ARTICLES BETWEEN TWO CONVEYORS This invention relates to transfer apparatus for exchanging articles between two conveyors. One application, to which the invention is particularly though not exclusively applicable, is to apparatus for transferring molds for ceramic blanks or the like between a first conveyor, for instance associated with a molding machine, and a second conveyor which is associated, for instance, with a drier, and receives molds occupied by blanks from the first conveyor and delivers empty molds back to it, twice as many molds being disposed one beside the other on the second conveyor as on the first conveyor.

According to the present invention, in transfer apparatus for exchanging articles arranged in one line along a first conveyor with articles arranged in two or more lines along a second conveyor, the conveyors are advanced step by step but the second conveyor is advanced only at alternate steps of the first conveyor.

Thus, in one form of the invention, transfer apparatus for exchanging articles arranged in one line along a first conveyor of endless chain type with articles arranged side by side in two or more lines along a second conveyor, also of endless chain type, arranged in line with the first conveyor end to end, includes means for plates each conveyor step by step by a distance corresponding to the spacing of the articles in a line, a step of the second conveyor only being effected with alternate steps of the first conveyor, means for transferring articles from the first conveyor to a first passing position between the conveyors and then alternately to whichever line of the second conveyor has a vacant place, and means for transferring articles alternately from one or the other line of the second conveyor to a second passing position laterally spaced from the first passing position, and then to the line of the first conveyor.

More particularly in the ceramics industry, the automation of manufacturing process is faced with the problem that a processing system, which acts on each individual workpiece for only a brief time, must be interlinked with another apparatus, which treats each individual workpiece for a very much longer period of time. This applies, for instance, to the manufacture of plates from ceramic blanks. The plates are formed in a few seconds by a molding machine and then, while still lying on their molds, they must stay in a drier until they have attained the so-called leather-hard condition in which they can be removed from the molds for further processing, whereafter the molds are returned to the molding machine and used there again. In an instance of this kind it would not be advisable to make the same conveyor, which conveys the molds with the blanks away from the molding machine and returns empty molds thereto, to run through the drier also, since the view of the relatively high conveying speed of the conveyor, adapted to the operating speed of the molding machine, the distance covered by the conveyor in the drier would have to be very long for the blanks to stay long enough in the drier. When using a common conveyor for the molding machine and the drier, conditions in the drier become particularly unfavorable if it is associated with a modern molding machine, which simultaneously processes two or more blanks arranged side by side on the conveyor, the blanks being arranged in a number of longitudinal lines along the conveyor. In this case the distances between the individual molds transversely of the conveying direction must be substantially larger than the space required for each individual mold, so that the individual molding devices do not impede one another. If the same conveyor also passes through the drier, the space left between two molds disposed one beside the other on the conveyor is not used in the drier.

It is, therefore, convenient for the molds with the blanks to be conveyed through the drier by a separate conveyor on which twice as many molds are disposed one beside the other as on the conveyor of the molding machine.

By means of this invention, the molds delivered with the blanks from one conveyor can be exchanged for the empty molds returned by a second conveyor in a very simple and reliable manner.

In one convenient form the apparatus includes two carriers (which may, for example, be arranged to grip the articles) arranged to reciprocate horizontally in opposite directions between the two conveyors so that while one carries an article from the first conveyor to the second conveyor, the other carries an article from the second'conveyor to the first conveyor; the paths of the carriers being chosen so as to avoid one another. Each carrier may be supported by a carriage mounted to travel in a direction parallel to the length of the conveyor, the carrier being mounted to move transversely relative to the carriage to align itself with either line of articles on the second conveyor and to avoid collision with the companion carrier.

As indicated above, the invention is applicable in cases where articles are arranged in two longitudinal lines on the first conveyor and in four longitudinal lines on the second conveyor. In such a case the apparatus may include four carriers carried in pairs by two carriages one of which forms a bridge below which the other can pass. Thus each carrier may be associated with one longitudinal line of articles on the first conveyor and two longitudinal lines of articles on the second conveyor on one side of its longitudinal central plane. The carriages may be connected to the two runs of an endless belt (such as a chain) so as to be simultaneously moved in opposite directions. This provides a simple means of avoiding inaccuracy in matching the timing of the movements of the carriages. Conveniently each carrier is mounted on a pivoted arm the pivotal axis of which lies in the vertical central plane between the two longitudinal lines of articles of the second conveyor.

The pivotal axis may itself be vertical.

In one form of the invention the transverse movement of a carrier is controlled by a cam follower cooperating with a stationary cam rail extending in the direction of movement of the carriage, at least a part of the cam rail being movable to modify the transverse movement of the carrier so as to pick up or deliver articles to or from different lines in the second conveyor in alternate steps. The two movable cam rails associated with carriers that pass one another on each movementof the carriages may be attached to a common transverse carriage. Where the first conveyor has two longitudinal lines of molds and the second transverse carriages moving in opposite directions and associated respectively with the carriers on opposite sides of the longitudinal central plane.

The transverse movements of each carrier can be controlled by moving the whole of the cam rail associated with it. The cycle of movement required is, however, achieved more simply if the movable cam rail extends along half the distance of travel of the carriages and in one position forms a continuation ofa fixed cam rail at the center. In this way the inert mass of the movable cam rails can be reduced so that they can be more readily reciprocated in rapid succession.

Conveniently, particularly in the case of molds for ceramic blanks, each article is retained on the conveyors in a recess from which it can be removed only in an upwards direction. To avoid the necessity for the grippers to reciprocate vertically as well as horizontally, each conveyor may be provided with one or more lifters which can be moved upwards through holes in the conveyor to lift an article to a carrier or lower it from a carrier. If the second conveyor carries four lines of articles side by side, two inner lifters can reciprocate vertically alternately with two outer lifters.

The invention may be put into practice in various ways but one specific embodiment will be described by way of example with reference to the accompanying drawings in which:

FIG. 1 is a highly simplified side elevation of the two adjacent ends of two conveyors and a transfer device interconnecting the conveyors;

FIG. 2 is a plan view corresponding to FIG. 1, omitting the transfer device;

FIG. 3 is a diagrammatic section, to a somewhat enlarged scale, taken along the line III-III in FIG. 1, with further details;

FIG. 4 is a side elevation of the transfer device, showing further details;

FIG. 5 is a plan view corresponding to FIG. 4;

FIGS. 6a6f are diagrams showing in a simplified manner details of FIG. 5 at various successive times; and

FIGS. 7a and 7b are also diagrams showing different details of FIG. 5 at successive times.

The object of the embodiment illustrated is to exchange molds, each of which is occupied with a ceramic blank and is disposed on a first conveyor 1, for empty molds disposed on a second conveyor 2. The first conveyor 1 runs through a known molding machine (not shown) in'which ceramic disc-shaped blanks are deformed into plates, and the second conveyor 2 runs through a known drier (not shown) in which enough moisture is removed from the blanks to enable them to so moved from the molds in the so-called leather-hard condition. Of the two conveyors l, 2, in each case two deflecting wheels 10, spaced apart along a common shaft are shown, over which chains 11, 12; 21, 22 run. Suspended from the two chains of each conveyor at uniform distances are oscillating plates 1315; 2325 which will be conventionally referred to as swings. Each of the swings of the first conveyor 1 is formed with two mold recesses 18 disposed symmetrically on opposite sides of the common central plane of the two conveyors; in contrast, each of the swings of the second conveyor 2 is recesses 27 and two outer recesses 28, also symmetrically arranged.

The transfer device comprises two carriages 30, 40 each of which is provided with two carriers in the form of grippers for the molds, and which can move between end positions on two guide rods 31, 41 extending parallel to the lengths of the two conveyors 1, 2. The two end positions of one carriage 30 are determined by end stops 32 adjustably attached to the associated guide rods 31. As shown diagrammatically in FIG. 3, the two c riages are do disposed symmetrically in relation to the common central plane 26 of the two conveyors that one carriage 30 brid es the second carriage 40 and can be moved over itwithout touching it. Two gripper arms 33, 43 are pivotallymounted or. each of the two carriages 30,40. The pivoting axes 34, 44 of the gripper arms 33 each extend vertically exactly in the center between the two planes in which the inner and outer recesses 27, 28 on each side of the longitudinal central plane are disposed. At the bottom of each gripper arm 33, 43 is a gripper 35, 45. Also disposed on each gripper arm 33, 43 is arm, at a distance from its pivoting axis 34, 44, is a cam follower 36, 46. Each of the two gripper arms 33 is so connected by a spring 37 to its gripper carriage 30 that the arms 33 tend to pivot away from one another; in contrast, the two gripper arms 43 are interconnected by a spring 47 so as to tend to pivot towards one another (see FIG. 5).

Each of the grippers 35, 45, which are identical, includes a yoke 50 which is attached to the associated gripper arm 33, 43 and, pivoted to each end of the yoke is a two-armed lever 51. The top ends of the two levers 51 of each gripper are so interconnected by a pneumatic piston-andcylinder unit 52, that when compressed air is supplied to the cylinder via a flexible hose 53, the bottom arms of the levers come towards each other and grip a mold 54, made, for instance, of gypsum. The mold, shown in FIG. 4 as held by the gripper 35, is empty, while the mold held by the gripper 45 is occupied by a freshly molded plate 55.

To enable the grippers 35, 45, which can move only in a in plane in the embodiment illustrated, to engage with the gypsum lever 71 54, which are normally disposed in the recesses 18; 27, 28 of the two conveyors l, 2, and to lower the molds carefully again into the recesses, after they have been exchanged between the conveyors, a lifter 18'; 27'; 28' is associated with each recess in that particular swing 14; 24 of each conveyor which is in the transfer position. The lifters are mounted to move up and down between an upper position, shown in FIG. 4 for the lifters 18, 28; and a lower position shown for the lifter 27'. The two lifters 18' associated with the recesses 18 in the swing 14 of the first conveyor 1 are rigidly connected to one another and controlled by a common cam disc 18"; correspondingly, the two lifters 27 associated with the inner recesses 27 in the swing 24 of the second conveyor 2, and the two lifters 28' associated with the outer recesses 28 in the swing 24, are interconnected in pairs and controlled by a cam disc 27", 28".

The guide rods 31, 41 of the two carriages 30, 40 in attached to two fixed bridges 61, 62 spaced apart, and lever 71 transversely over the adjacent ends of the two conveyors l, 2. Attached to the bridges 61, 62 is a bottom fixed cam rail 35' for each gripper 35 of the upper carriage 30, and a top fixed cam rail 45 for each gripper 45 of the lower carriage 40. As shown in FIGS. 5 and 7, the two bottom fixed cam rails 35' are straight, while the two top fixed cam rails 45' have curved portions in their centers. Part of each bottom fixed cam rail 35' is covered by a bottom movable cam rail 35", and part of each top fixed cam rail 45 is covered by a top movable cam rail 45". The movable cam rails 35 45" each extend symmetrical only over half the length of the associated fixed cam rail 35 45', are summetrical in pairs in relation to one another, and are attached in pairs to two transverse carriages 63. The two transverse carriages 63 can be displaced on guide rods 64 which extend parallel with the bridge 62 to which they are attached. Mounted on each transverse carriage 63 is a cam follower roller 65 which bears against a cam disc 67 under the force of a spring 66 interconnecting the two transverse carriages. Attached to each fixed cam rail 35, 45 is a transverse guide 68 in which the associated movable cam rail 35"; 45 is guided.

The drive for the movement of the two gripper carriages 30, 40 in opposite directions along the guide rods 31, 41 comprises a lever 71 (FIG. 4) which can pivot around a fixed axis 72 and bears against a cam disc 73. Attached to the free end of the lever 71 is the end of a cable 74 which runs over two pulleys 75, 76 mounted on the bridge 62, and over two pulleys 77, 78 mounted on the bridge 61, and has its other end connected through a tension spring to a fixed point. Between the two deflecting rollers 76, 77 the cable 74 is attached to the upper gripper carriage 30. Attached to the lower gripper carriage 40 is the bottom run of an endless chain 80 which runs over two pulleys 81, 82 on the two fixed bridges 61, 62 and whose top run is attached to the upper gripper carriage 30.

The apparatus described operates as follows:

The two conveyors 1, 2 are moved by a drive, which can be of conventional construction (not shown), in steps corresponding to the spacing between adjacent groups of swings 1315; 23-25, in such a way that the second conveyor 2 performs a step only during or after each alternate step of the first conveyor 1. The cam disc 73 is so connected to the drive of the two conveyors, that at or after each step of the first conveyor l the cam disc 73 performs half a rotation, so that the lever 71 occupies its lower position (shown in FIG. 4) after one step by the first conveyor, and its upper position after each following step. correspondingly, each of the two gripper carriages 30, 40 occupies after a step by the first conveyor its position shown in FIGS. 4 and 5 and exchanges these positions after the next step of the first conveyor.

The cam disc 67, symmetrical about its axis of rotation, also performs a quarter of a revolution at or after each step by the first conveyor 1, so that the two transverse carriages 63 also reciprocate horizontally in opposite directions with each pair of cam rails 35", 45" in time with the conveyor movement.

The cam followers 36, 46 of the gripper arms 33, 43, bear against the two associated cam rails 35', 35"; 45, 45" under the force of the springs 37, 47, and are pivoted in the manner shown in FIGS. 6a6f during the reciprocating movement of the gripper carriages 30, 40 on the one hand and the transverse carriages 63 on the other. FIGS. 6a6f show in a simplified manner only the lower halves of the carriages 30, 40 as shown in FIG. 5, and of the swing 14; 24 of the two conveyors 1, 2 which happens to occupy the transfer position. In FIGS.

6a6f an empty recess 18; 27 or 28 of the swings 14, 24 is shown in each case by a chain-dot circle, while an unoccupied gypsum mold 54 is shown by a solid circle, and a gypsum mold occupied by a plate 55 is shown by two concentric solid circles.

The position of the gripper carriages 30, 40 and the grippers 33, 43 in FIG. 6a corresponds to the position shown in FIG. 5, in which the gripper 35 is suspended from the gripper arm 33 has taken an empty mold 54,"from the swing 24 of the second conveyor 2, and the gripper 45 suspended from the gripper arm 43 has taken a mold occupied by a workpiece 55 from the swing 14 of the first conveyor 1 As the two carriages 30, 40 now move to a passing position, one above the other, the gripper arm 33 moves to the right without pivoting, since its cam follower 36 runs along the straight fixed cam rail 35', as shown in FIG. 7a. On the other hand, the gripper arm 43 which simultaneously moves to the left, pivots through about 90 in an anticlockwise direction, as shown in FIG. 6b, since its cam follower 46 runs along the recessed fixed cam rail 45', as shown in FIG. 7a. This pivoting of the gripper arm 43 serves to prevent a collision between the two meeting grippers and the molds carried thereby.

During the second half of the movement away from the passing positions shown in FIG. 6b to the position of FIG. 6cthe cam follower 46 running up along the curved movable cam rail 45", pivots it back to its initial position. After the first change of position of the two carriages 30, 40, the gripper arms 33, 43 occupy the position shown in FIG. 60 in which the gripper 35 passes the empty mold 54 to the lifter 18, which at that moment occupies its upper position as shown in FIG. 4; at the same time the gripper 45 delivers the mold occupied by a plate 55 to the lifter 28', which also occupies its upper position. Then the two lifters I8, 28' lower the molds into the corresponding recesses I8; 28 in the swing I4; 24 and move into their lower positions, as shown for the lifter 27 in FIG. 4.

The first conveyor 1 then moves on by one step in the direction indicated by the arrow in FIG. 1, so that the swing 14 is previously in the transfer position passes into the position 15, while a fresh swing 13, which bears a mold occupied by a plate 55 on each side of the longitudinal central plane 26 moves into the transfer position 14. At the same time, the cam rails 35"; 45" move out of their position shown in FIGS. 5 and 7a into the position shown in FIG. 7b. The cam follower 46 of the gripper arm 43 takes part in this displacement of the movable cam rails 35"; 45", so that, as shown in FIG. 6d, the gripper arm 43 is again pivoted through about 90 anticlockwise, and the associated gripper 45 arrives above an empty mold 54 which has been raised by the lifter 27 from an inner recess 27 in the swing 24.

As soon as the grippers have taken the molds, the lifters I8,

27 are again lowered by their cam discs 18"; 28", and the carriages 30, 40 start a fresh longitudinal movement.

As the carriages are approaching one another, to the passing position of FIG. 6e, the gripper arms 33, 43 remain in their angular position, as the cam follower 36 rides on the straight edge of the fixed cam rail 35, and the cam follower 46 rides on the straight edge of the fixed cam rail 45, as shown in FIG. 7b, so that the grippers 35, 45 with the molds pass one another.

When the upper carriage 30 has moved over the lower earriage 40, and the carriages are again moving away from one another, the cam follower 36 of the gripper arm 33 runs up along the movable cam rail 35", and the cam follower 46 of the gripper arm 43 runs along the curved portion of the fixed cam rail 45 (shown on the right-hand side in FIGS. 5 and 7b), so that both gripper arms 33, 43 perform a pivoting movement and arrive in the position shown in FIG. 6]" where they each deliver the mould which they are carrying to a lifter 27; 18.

As soon as this has been done, and all the lifters have arrived at their lower positions, the two conveyors I and 2 both move on by .one step. At the same time the cam rails 35"; 45" move out of their position shown in FIG. 7b back into the position shown in FIG 7a, and cause the gripper arm 33 to pivot in the direction indicated by the arrow in FIG. 6f, thus returning to the starting condition shown in FIG. 60, so that a fresh cycle can start.

It will be obvious to those skilled in the art that various changes may be made without departing from the scope ofthe invention and the invention is not to be considered limited to what is shown in the drawings and described in the specification.

What we claim is:

1. Transfer apparatus for exchanging articles arranged in a line along a first endless conveyor with articles arranged in n equals two or more lines along a second conveyor, including means for advancing each conveyor step by by a distance corresponding to the spacing of the articles in a line on it, a step of the second conveyor being effected only at each n"' step of the first conveyor, and means for exchanging articles between the first and second conveyor in a cycle such that an article on the first conveyor is exchanged for an article in one line on the second conveyor, the first conveyor is then advanced a step, and the next article in the same line on the first conveyor is then exchanged for an article in a different line on the second conveyor.

2. Apparatus as claimed in claim 1 in which each conveyor is provided with one or more lifters which can be moved upwards through holes in the conveyor to lift an article to a carrier or lower it from a carrier.

3. Apparatus as claimed in claim 1 for exchanging articles arranged in one or more lines along a first conveyor ofendless chain type with articles arranged in twice as many lines along a second conveyor, also of endless chain type, arranged in line with the first conveyor end to end, a step of the second conveyor only being effected with alternate steps of the first conveyor, the exchanging means including means for transferring articles from a line of the first conveyor to one of two passing positions which are laterally spaced from one another between the conveyors, and thence to one line of the second conveyor while transferring an article from the said line of the second conveyor to the other passing position, and thence to the said line of the first conveyor and thereafter transferring an article from the same line of the first conveyor to one of the passing positions and thence to another line of the second conveyor, while transferring an article from the said other line of the second conveyor to the other passing position and thence to the same line of the first conveyor.

4. Apparatus as claimed in claim 3 including two carriers arranged to reciprocate horizontally in opposite directions between the two conveyors so that while one carries an article from the first conveyor to the second conveyor the other carries an article from the second conveyor to the first conveyor, the paths of the carriers being chosen so as to avoid one another.

5. Apparatus as claimed in claim 4 in which each carrier is supported by a carriage mounted to travel in a direction parallel to the length of the conveyor, the carrier being mounted to move transversely relatively to the carriage to align itself with either line of articles on the second conveyor and to avoid collision with the companion carrier.

6. Apparatus as claimed in claim 5 in which the two carriages are connected to the two runs of an endless belt so as to be simultaneously moved in opposite directions.

7. Apparatus as claimed in claim 5 in which the transverse movement of a carrier is controlled by a cam follower cooperating with a stationary cam rail extending in the direction of movement of the carriage, at least a part of the cam rail being movable to modify the transverse movement of the carrier so as to pick up or deliver articles to or from different lines in the second conveyor in alternate steps.

8. Apparatus as claimed in claim 7 in which the two movable cam rails associated with carriers which pass one another on each movement ofthe carriages are attached to a common transverse carriage.

9. Apparatus as claimed in claim 7 in which each movable cam rail is associated with a fixed cam rail which in one position of the movable cam rail forms the sole guide for the cam follower.

10. Apparatus as claimed in claim 9 in which the movable cam rail extends along half the distance of travel of the can riages and in one position forms a continuation of the fixed rail at the center.

11. Apparatus as claimed in claim 7 in which the cam rails for a pair of carriers comprise fixed cam rails having portions operative irrespective of the position of any movable portions for guiding one carrier between the position of an article on the first conveyor and a first passing position, and the other carrier between the said position of such an article and a second passing position 12. Apparatus as claimed in claim 11 in which each fixed cam rail has a further portion which is straight and serves to guide the respective carrier from the position of an article in one or other line on the second conveyor and one or other passing position which is aligned therewith, and which includes movable cam rails one or other of which is advanced to mark the associated straight fixed portion and is curved to guide its carrier between the same passing position and the position of an article on the second conveyor in a line not in line with the said passing position.

13. Apparatus as claimed in claim ill in which one of the passing positions is aligned with that of articles on the first conveyor and the fixed portion of the cam rail guiding a carrier between those positions is also straight.

14. Apparatus as claimed in claim 4 in which each carrier is mounted on a pivoted arm, the pivotal axis of which lies in the vertical central plane between the two longitudinal lines of articles of the second conveyor.

15. Apparatus as claimed in claim 14 in which the pivotal axis of the arm is vertical.

16. Apparatus as claimed in claim 3 arranged to exchange articles arranged in two longitudinal lines on the first conveyor with articles arranged in four longitudinal lines on the second conveyor.

17. Apparatus as claimed in claim 16 including four carriers carried in pairs by two carriages one of which forms a bridge below which the other can pass.

i8. Apparatus as claimed in claim 16 in which each carrier is associated with one longitudinal line of articles on the first conveyor and two longitudinal lines of articles on the second conveyor on one side ofits longitudinal central plane.

ll 3'. Apparatus as claimed in claim 16 including two separate transverse carriages moving in opposite directions and as sociated respectively with the carriers on opposite sides of the longitudinal central plane.

30. Apparatus as claimed in claim to in which cam rails for guiding a pair of carriers comprise fixed cam rails having portions operative irrespective of the position of any movable portions for guiding one carrier between the position of an article on the first conveyor and a first passing position, and the other carrier between the said position ofsuch an article and a second passing position, and in which two inner lifters can reciprocate vertically alternately with two outer litters of the second conveyor.

2i. Apparatus as claimed in claim 3 in which each conveyor is provided upwards with one or more lifters which can be moved upwards through holes in the conveyor to lift an article to a carrier or lower it from a carrier.

22. Apparatus as claimed in claim 1 including two carriers arranged to reciprocate in opposite directions between the two conveyors so that while one carries an article from the first conveyor to the second conveyor the other carries an arti cle from the second conveyor to the first conveyor, the paths ofthe carriers being chosen so as to avoid one another.

A conveyor system for conveying molds for ceramic blanks past a molding machine and a drier, including a first conveyor on which the molds are arranged in one or more longitudinal lines, a second con. cyor on which they are arranged in a greater number of longitudinal lines, and, for exchanging molds between the two conveyors, transfer apparatus as claimed in claim ll.

24. A system as claimed in claim 23 in which the second conveyor has four longitudinal lines of molds, and the first conveyor has two such rows spaced apart a distance equal to the spacing between the outermost rows on the second convevor. 

1. Transfer apparatus for exchanging articles arranged in a line along a first endless conveyor with articles arranged in n equals two or more lines along a second conveyor, including means for advancing each conveyor step by step by a distance corresponding to the spacing of the articles in a line on it, a step of the second conveyor being effected only at each nth step of the first conveyor, and means for exchanging articles between the first and second conveyor in a cycle such that an article on the first conveyor is exchanged for an article in one line on the second conveyor, the first conveyor is then advanced a step, and the next article in the same line on the first conveyor is then exchanged for an article in a different line on the second conveyor.
 2. Apparatus as claimed in claim 1 in which each conveyor is provided with one or more lifters which can be moved upwards through holes in the conveyor to lift an article to a carrieR or lower it from a carrier.
 3. Apparatus as claimed in claim 1 for exchanging articles arranged in one or more lines along a first conveyor of endless chain type with articles arranged in twice as many lines along a second conveyor, also of endless chain type, arranged in line with the first conveyor end to end, a step of the second conveyor only being effected with alternate steps of the first conveyor, the exchanging means including means for transferring articles from a line of the first conveyor to one of two passing positions which are laterally spaced from one another between the conveyors, and thence to one line of the second conveyor while transferring an article from the said line of the second conveyor to the other passing position, and thence to the said line of the first conveyor and thereafter transferring an article from the same line of the first conveyor to one of the passing positions and thence to another line of the second conveyor, while transferring an article from the said other line of the second conveyor to the other passing position and thence to the same line of the first conveyor.
 4. Apparatus as claimed in claim 3 including two carriers arranged to reciprocate horizontally in opposite directions between the two conveyors so that while one carries an article from the first conveyor to the second conveyor the other carries an article from the second conveyor to the first conveyor, the paths of the carriers being chosen so as to avoid one another.
 5. Apparatus as claimed in claim 4 in which each carrier is supported by a carriage mounted to travel in a direction parallel to the length of the conveyor, the carrier being mounted to move transversely relatively to the carriage to align itself with either line of articles on the second conveyor and to avoid collision with the companion carrier.
 6. Apparatus as claimed in claim 5 in which the two carriages are connected to the two runs of an endless belt so as to be simultaneously moved in opposite directions.
 7. Apparatus as claimed in claim 5 in which the transverse movement of a carrier is controlled by a cam follower cooperating with a stationary cam rail extending in the direction of movement of the carriage, at least a part of the cam rail being movable to modify the transverse movement of the carrier so as to pick up or deliver articles to or from different lines in the second conveyor in alternate steps.
 8. Apparatus as claimed in claim 7 in which the two movable cam rails associated with carriers which pass one another on each movement of the carriages are attached to a common transverse carriage.
 9. Apparatus as claimed in claim 7 in which each movable cam rail is associated with a fixed cam rail which in one position of the movable cam rail forms the sole guide for the cam follower.
 10. Apparatus as claimed in claim 9 in which the movable cam rail extends along half the distance of travel of the carriages and in one position forms a continuation of the fixed rail at the center.
 11. Apparatus as claimed in claim 7 in which the cam rails for a pair of carriers comprise fixed cam rails having portions operative irrespective of the position of any movable portions for guiding one carrier between the position of an article on the first conveyor and a first passing position, and the other carrier between the said position of such an article and a second passing position.
 12. Apparatus as claimed in claim 11 in which each fixed cam rail has a further portion which is straight and serves to guide the respective carrier from the position of an article in one or other line on the second conveyor and one or other passing position which is aligned therewith, and which includes movable cam rails one or other of which is advanced to mark the associated straight fixed portion and is curved to guide its carrier between the same passing position and the position of an article on the second conveyor in a line not in line with the said passing position.
 13. ApparatUs as claimed in claim 11 in which one of the passing positions is aligned with that of articles on the first conveyor and the fixed portion of the cam rail guiding a carrier between those positions is also straight.
 14. Apparatus as claimed in claim 4 in which each carrier is mounted on a pivoted arm, the pivotal axis of which lies in the vertical central plane between the two longitudinal lines of articles of the second conveyor.
 15. Apparatus as claimed in claim 14 in which the pivotal axis of the arm is vertical.
 16. Apparatus as claimed in claim 3 arranged to exchange articles arranged in two longitudinal lines on the first conveyor with articles arranged in four longitudinal lines on the second conveyor.
 17. Apparatus as claimed in claim 16 including four carriers carried in pairs by two carriages one of which forms a bridge below which the other can pass.
 18. Apparatus as claimed in claim 16 in which each carrier is associated with one longitudinal line of articles on the first conveyor and two longitudinal lines of articles on the second conveyor on one side of its longitudinal central plane.
 19. Apparatus as claimed in claim 16 including two separate transverse carriages moving in opposite directions and associated respectively with the carriers on opposite sides of the longitudinal central plane.
 20. Apparatus as claimed in claim 16 in which cam rails for guiding a pair of carriers comprise fixed cam rails having portions operative irrespective of the position of any movable portions for guiding one carrier between the position of an article on the first conveyor and a first passing position, and the other carrier between the said position of such an article and a second passing position, and in which two inner lifters can reciprocate vertically alternately with two outer lifters of the second conveyor.
 21. Apparatus as claimed in claim 3 in which each conveyor is provided with one or more lifters which can be moved upwards through holes in the conveyor to lift an article to a carrier or lower it from a carrier.
 22. Apparatus as claimed in claim 1 including two carriers arranged to reciprocate in opposite directions between the two conveyors so that while one carries an article from the first conveyor to the second conveyor the other carries an article from the second conveyor to the first conveyor, the paths of the carriers being chosen so as to avoid one another.
 23. A conveyor system for conveying molds for ceramic blanks past a molding machine and a drier, including a first conveyor on which the molds are arranged in one or more longitudinal lines, a second conveyor on which they are arranged in a greater number of longitudinal lines, and, for exchanging molds between the two conveyors, transfer apparatus as claimed in claim
 1. 24. A system as claimed in claim 23 in which the second conveyor has four longitudinal lines of molds, and the first conveyor has two such rows spaced apart a distance equal to the spacing between the outermost rows on the second conveyor. 